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Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X

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John Wildgoose
Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 3, 2017 at 12:29:08 pm

Hi
So I had a good rummage around and could not find this answered, which means it's either not an issue or it's simple stuff for most of you and I'm dim for asking! Probably the latter. Anyway...

So I will be shooting on a new set up: GH5 through Atomos Ninja Inferno at 50p 10bit 4.2.2.

My projects are all 25p but I am thinking I should shoot/record everything in 50p 10bit so I can have the option (in FCP X) to have it either slo-mo or normal speed as 50p dumped into a FCP X 25p project will playback at normal speed, you HAVE TO do a speed change in order to get the slo-mo (as I understand it).

I have two questions:
1) how does FCP deal with the 50p in a 25p project? I need to know this as this will answer my second question.
2) what shutter speed would be best for a 50p clip that will eventually be used at 25p (i.e. at normal speed) in a 25p FCP X project?

If I can figure out what FCP X does with 50p footage in a 25p project I will know if it's ok to carry on shooting 50p at 100th/s, knowing it will play nicely at 25p, or if I will need to make a decision at the camera about whether to shoot for normal speed or slo-mo.

In a nutshell: Can I get away with shooting everything at 50p at 100th/s and have it look nice and natural at normal speed in a 25p FCP X project, or will it look odd going from 50p to 25p?


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Noah Kadner
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 4, 2017 at 5:09:55 am

Technically it will just do a speed change - whether it works aesthetically is subjective. Shoot some test footage.

Noah

FCPWORKS - FCPX Workflow
FCP Exchange - FCPX Workshops
XinTwo - FCPX Training


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 4, 2017 at 8:41:10 am

Thanks Noah, I will do that.
I was just interested in what exactly FCP does to the 50p in a 25p project to get it to play at normal speed! I know I maybe should not worry about what is going on under the hood, but I'm of that generation.

I'll do some more tests. I am not sure if it's anything to do with anything related, but I recently shot some 50p at 80th/s (at 8bit) and it just seemed a bit more natural. A little bit of softening through motion blur seemed to appeal.





Thanks for your response, appreciated.

John


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Noah Kadner
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 4, 2017 at 9:19:20 pm

Yeah the higher shutter speed you go above double your frame rate the more staccato the results will look. To get from 50 to 25 FCPX just throws away every other frame- as you would expect.

Noah

FCPWORKS - FCPX Workflow
FCP Exchange - FCPX Workshops
XinTwo - FCPX Training


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 5, 2017 at 5:19:41 am

Hi Noah
...and in halving the frame rate it halves the shutter speed? This is crucial as the look of the clip is so clearly affected by the shutter speed.

I'm going out today to do some tests. People, water, foliage, traffic. Plus some varieties of shutter angle/speed at 50p to see exactly what happens when it's kept at 25p in FCP X. I'll also shoot 25p of the same scenes at half the shutter speed I shot the 50p at to see if there's any difference between it and the 50p that doesn't have the speed change applied.

I guess I am trying to prove the hypothesis that 50p shot at 100th/s but left at 25p in the FCP X timeline will look the same as 25p shot at 50th/s (or 80th/s and 40th/s etc). This will then dictate whether I can shoot everything at 50p and quit agonising!

I'll be back I guess.

John


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Claude Lyneis
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 7, 2017 at 5:35:52 am

[Noah Kadner] "Yeah the higher shutter speed you go above double your frame rate the more staccato the results will look. To get from 50 to 25 FCPX just throws away every other frame- as you would expect.

Noah"


I frequently shoot at 60 p for sports (lacrosse) because it definitely improves the look when using slow motion, 50% speed. So the project is set up at 60 p and the motion looks normal. Is FCPX really throwing away every other frame or is it just running 60 frames per second? Generally the output is compressed using Compressor set up for Youtube. Once though Compressor, the quicktime inspector shows the frame rate to be 60 fps (59.94). So in this case it doesn't seem to be throwing frames away. I guess if you have a 30 f/s video and you insert some 60p into it, it may shed frames and in this case you lose half of the light and get less motion blur.


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Paul Golden
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 5, 2017 at 7:03:40 pm

At the risk of being impertinent, what's the reason for wanting to do this?
While it sounds like some sort of problem solver to shoot at 50fps for use at 25, shooting this way is rarely done as a matter of course for several reasons:
1) Double the amount of data
2) Post processing headaches
3) No apparent benefit for most of the footage you shoot.

Unless you have a really good reason (need lots of slow motion), I can't see why you'd want to shoot this way for normal footage. You asked a tech question and folks have answered it diligently, but I'd go back to the original reason of why you'd want do it if you don't have to? It seems like overkill.


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Paul Golden
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 5, 2017 at 10:51:10 pm

I forgot one other reason not to: You need twice as much light! :-)


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 6, 2017 at 7:45:07 am

Twice as much light! Yes, but to be honest I shoot a lot with fast primes, often wide open, so anything that helps me dump light is a blessing!

Thanks Paul.

And re: your comment about diligently answered tech question. Yes, I have tried hard to make sure people who have contributed to help have had that help acknowledged. It's a great forum, obviously brimming with good people who not only possess a huge amount of high quality knowledge, but are also happy to impart it for the good of all. Open source knowledge is a wonderful thing.

I will endeavour to 'put something back' in whatever way I can. Surely these 30 years have given me something to contribute!


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 6, 2017 at 7:35:17 am

Hi Paul
That's a very fair point and I can see why many/most people might scratch their head at such a notion.

Maybe I should have explained why I wanted to do this, but to be fair to myself, the answer is so ingrained in my mind it never occurred to me! So my bad, I should have explained.

I'm a veteran of 30 years shooting stills, video is increasingly (and excitingy) becoming a bigger part of my remit these days and I am trying to get up to speed with all the endless and shifting (not to say expensive) technology.

One of the things that has become apparent is a need for 'generic' moving images. I've been asked to shoot stock and b-roll/cutaways for clients recently, enough to make me jump on this difficult/rewarding learning curve. For instance, one client has a web site full of interviews with industry experts and they decided their 'talking heads' needed spicing up. So they sent me off to Asia to shoot b-roll to cut into their web embedded videos. Sweet gig? Yes, but it did immediately highlight some shortcomings in my process, not to say my skillset.

If you have a few minutes (and a cup of coffee), here's my cut from that Asia shoot. Please forgive the terrible 'standards' short comings. I'm a neophyte remember!



As you'll now hopefully appreciate, to be able to shoot all of that at 50p and make a choice in the cut what should stay 100% and what could go half speed would be a major advantage.

cheers
John


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Kevin Rag
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 7, 2017 at 5:57:18 am

Hey John,
What camera lenses did you use? I like the look:)

K


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 8, 2017 at 7:01:36 am

I think most of this was shot on a 70-200 f2.8 as it's very adaptable for fast changing subjects that move around without control.

More predictable shots are done on f1.4 and f1.2 primes. This was all shot on 5DIIIs with a SmallHD monitor. I've changed a lot of the workflow now and I think I'd get a lot more detail in the shadows and highlights. But for small videos embedded in a web site it worked, the editor was certainly very happy with what I supplied, so that was my benchmark for quality at the time.

I have changed the gear too. I now shoot with a GH5, metabones speed adaptor and primarily a 16-35 f2.8 (giving me an effective open iris of f1.8). This allows me to get closer and still see a lot, and it works nicely with my favoured compositions. On a shoot I'd take the 70-200 f2.8 as well. I have a problem with the faster 24-70 as the zoom telescopes making it impractical to use in my Tilta rig with the matte box. But that might mean giving up a stop (f4 which would make me unhappy).


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Kevin Rag
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 8, 2017 at 7:08:48 am

Thanks John:) Just picked up a GH5. I already have a few MFT primes. Will get a Speedbooster and the Sigma soon.

K


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Claude Lyneis
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 8, 2017 at 3:57:17 am

Really looks great. Love the bokah and the color depth.


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 8, 2017 at 7:03:56 am

thanks Claude,
I have to say given how much I've moved on since that shoot, I'd love to have another stab at it, I'm sure I'd get a lot more from it (and the highlights and shadows too!!).


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 8, 2017 at 9:28:59 am

ok, I've done some tests to see and my conclusion is that you can't shoot 50p and run it at normal time in a 25p project as it looks too staccato, even shooting it at 80th (compromise!).

Oddly, I did my test of the 25p shot clip at 40th as I like the little bit of extra motion blur it gives, but if you do that with a 50p clip at 80th/s slowed down by 50% it shows a bit too much motion blur, so I went back to 100th/s and... much better! So that doesn't add up! I've added that clip to the test (last one) for you to see what I'm on about.

Anyway, here you go.






Interestingly, I just watched this on a 49inch 4K monitor and the 1080p at 10bit from the GH5 almost cuts it!

I've avoided adding the ubiquitous heavy metal track to make it appear more exciting than it is!


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Claude Lyneis
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 9, 2017 at 4:56:05 pm

Very interesting. After a few tries, I could see a difference in how your fingers looked as you tightened a screw. The 50p inserted into a 25 p project did show a slight lack of smoothness (less motion blur). Of course this is viewed on a 27 inch mid 11 Mac not a 5k screen.

One thing I am not sure of. If some a video using some 50 p and some 25 is mixed as you have done first with the 50p inserted into to 25p project and then second with the 25p inserted into a 50 p project, is the result the same?


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John Wildgoose
Re: Shutter angle/speed for 50p shot for 25p edit? GH5, Atomos Ninja Inferno, FCP X
on Sep 10, 2017 at 7:16:57 am

Hi Claude
It didn't occur to me to test it this way, as I can't see any material benefit. But if it's a 50p project then I'm assuming shoving a 25p clip in it is going to make the clip stagger horribly due to a 2:1 frame deficiency. Unless you sped the clip up of course, and why would you do that, other than to replicate that old 1960's trick of making a car chase look faster, but horribly, horribly wrong at the same time?


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